From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: C and Emacs Lisp code parts Date: Fri, 01 Jul 2016 16:01:11 +0300 Message-ID: <83twg9tsvc.fsf@gnu.org> References: <624c3d37-c829-7187-a699-7d7bbc211a20@online.de> <83ziq1u668.fsf@gnu.org> <83y45lu2up.fsf@gnu.org> <54f5d80c-f20b-31aa-b438-401984fcb5b8@online.de> Reply-To: Eli Zaretskii NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1467378202 15228 80.91.229.3 (1 Jul 2016 13:03:22 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 1 Jul 2016 13:03:22 +0000 (UTC) Cc: emacs-devel@gnu.org To: Andreas =?utf-8?Q?R=C3=B6hler?= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Jul 01 15:03:17 2016 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bIy6A-0007vv-PO for ged-emacs-devel@m.gmane.org; Fri, 01 Jul 2016 15:03:10 +0200 Original-Received: from localhost ([::1]:33470 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bIy64-0007G8-Vo for ged-emacs-devel@m.gmane.org; Fri, 01 Jul 2016 09:03:05 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:49959) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bIy4r-0006G3-QZ for emacs-devel@gnu.org; Fri, 01 Jul 2016 09:01:50 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bIy4m-0004mm-3x for emacs-devel@gnu.org; Fri, 01 Jul 2016 09:01:48 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:58274) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bIy4m-0004mh-0e; Fri, 01 Jul 2016 09:01:44 -0400 Original-Received: from 84.94.185.246.cable.012.net.il ([84.94.185.246]:1514 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1bIy4i-0007bS-3y; Fri, 01 Jul 2016 09:01:42 -0400 In-reply-to: <54f5d80c-f20b-31aa-b438-401984fcb5b8@online.de> (message from Andreas =?utf-8?Q?R=C3=B6hler?= on Fri, 1 Jul 2016 14:25:22 +0200) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:205034 Archived-At: > Cc: emacs-devel@gnu.org > From: Andreas Röhler > Date: Fri, 1 Jul 2016 14:25:22 +0200 > > On 01.07.2016 11:25, Eli Zaretskii wrote: > > > > So yes, we need numbers to make rational decisions about this. > > Sorry, but that's irrational. ??? Comparing without numbers, based on "feelings", is irrational! It is a well-known fact that reasoning about code optimizations without measurements is a fallacy that causes optimizations in wrong places. > Compare doesn't need numbers. To compare implementations in C an > exec is needed - which doesn't exist yet. If written, the reason > basically is gone, because C will be faster - unless something went > wrong, which is a case for debugging rather than benchmarks. I'm not against writing it, I'm just saying that before accepting a C implementation instead of a Lisp one, we should consider the speedup factor, because rewriting in C has its downsides (which you mentioned) that have to be weighed against the advantages.